1 function updateInventory(arr1, arr2) {
 2   // All inventory must be accounted for or you‘re fired!
 3   
 4   
 5   var arr = [];  // 用于存放当前货物名称的数组  
 6   var obj = {};  // 用于存放当前货物名称和数组下标的对象
 7   var arr1Len = arr1.length - 1;
 8   
 9   // 遍历当前货物的名称，下标和名称
10   for (var i = 0; i < arr1.length; i++) {
11     arr.push(arr1[i][1]);
12     obj[arr1[i][1]] = i;
13   }
14   
15   // 更新当前数组
16   for (var j = 0; j < arr2.length; j++) {
17     // 如果新进货物已存在，更新数量（加法）
18     if (arr.indexOf(arr2[j][1]) !== -1) {
19       var arr1Index = obj[arr2[j][1]];
20       arr1[arr1Index][0] += arr2[j][0];
21     }
22     // 如果新进货物不存在，加入到当前货物数组
23     else {
24       arr1.push(arr2[j]);
25       // 更新arr、obj
26       arr.push(arr2[j][1]);
27       arr1Len += 1;
28       obj[arr2[j][1]] = arr1Len;
29     }
30   }
31   
32   //排序
33   arr.sort();
34   var result = [];
35   for (var z = 0; z < arr.length; z++) {
36     result.push(arr1[obj[arr[z]]]);
37   }
38   return result; 
39   
40 }
41 
42 // Example inventory lists
43 // arr1
44 var curInv = [
45     [21, "Bowling Ball"],
46     [2, "Dirty Sock"],
47     [1, "Hair Pin"],
48     [5, "Microphone"]
49 ];
50 //arr2
51 var newInv = [
52     [2, "Hair Pin"],
53     [3, "Half-Eaten Apple"],
54     [67, "Bowling Ball"],
55     [7, "Toothpaste"]
56 ];
57 
58 updateInventory([[21, "Bowling Ball"], [2, "Dirty Sock"], [1, "Hair Pin"], [5, "Microphone"]], [[2, "Hair Pin"], [3, "Half-Eaten Apple"], [67, "Bowling Ball"], [7, "Toothpaste"]]);